The present invention relates to damper structures and more specifically to the reduction of low frequency noise in damper structures.
Air flow structures such as dampers are subject to self-generated noise which is a function of the velocity and pressure of the delivered air as well as the structural details of the air distribution system. Because the duct opens into the room or zone through one or more terminals, the noise may be delivered along with the conditioned air. There is an apparently random distribution of the noise but the noise generation is greatest at lower static pressures where a hollow whistle akin to that resulting from blowing over a bottle is produced. The noise generation is apparently the result of air separation at the hinge area due to the transition in the damper blade.